Suitable hemolysis index for low flow blood pumps

Abstract

1.Objectives: Blood pumps are used at 1-2L/min for pediatric VADs and 0.05-0.2L/min for blood purification. The hemolysis index is defined in ASTM-F1841 as NIH=TotalFreeHb*100L/time/flow. And the flow is restricted to 5±0.25L/min. If this is extended to low flow region, NIH value increases in a hyperbolic manner though plasma color does not change. 2.Method: A MERA centrifugal pump was operated in a circuit filled with bovine blood at constant 200mmHg and flow was changed every 30min for 1-6L/min. The change rate of the TotalFreeHb, δTFHB, was recorded. Next, the flow rate is kept at 4L/min and rotational speed was changed every 30min for 1400-3000rpm. 3.Results: The δTFHB did not show any positive correlation to flow. It rather showed positive correlation to rotational speed.4.Conclusion: Hemolysis index should not be divided by flow but δTFHB be used as it is. If necessary, δTFHB had better be divided by rotational speed.